With the development of communication technology, the demand for communication power supply also increases gradually, and a mode of paralleling modules is adopted in the system to adapt to the increase of the power demand and also can implement redundancy of the power module to improve reliability at the same time with the increase of the power. However, to implement a parallel connection of the rectifier power modules, the problem that the rectifier modules share different loads caused by the un-identical parameters of the rectifier module apparatuses must be overcome. The different loads of the rectifier modules make the output current of each module different, and the reliability of the system is reduced since part of the rectifier modules have large loads and some have rather small loads. To solve the problem of load equipartition, it is required to perform current sharing control. The method for implementing current sharing control has an analog mode and a digital mode. Since the rectifier current sharing implemented by the analog mode has disadvantages of low precision resulted from easy to be influenced by circumstance, needing a current sharing bus and limited number of parallel connections and so on, the current sharing solution of the digital mode gradually appears.
Currently, digital implementation for implementing the rectifier current sharing mainly has two types: one is average current method, that is, each rectifier module sends the output current of the local host in the way of communication, and then each rectifier collects the output current of all rectifiers in the system and calculates the average current, which is taken as a reference to perform current sharing control. Another is master-slave method, that is, the system has a master machine, which sends the local host current in the way of communication, and other rectifiers are slave machines, which follow the current of the master machine to reach the purpose of current sharing.
In the average current method, it needs to acquire the output currents of all rectifier modules in the parallel system, and the communication traffic also increases with the increase of the number of parallel connections. If the number of parallel connections is N, the communication traffic is N/2 times, which will cause a huge pressure on the communication and a bottleneck of the increase of the number of parallel connections.
In the master-slave method, only the master machine sends the current, which has no relationship with the number of parallel connections, the number of parallel connections is not limited in theory and is related to the signal attenuation of communication physical paths. However, in this method, because the existence of the master machine, the current sharing will fail when the master machine breaks down. To avoid this problem, a complicated fault detection mechanism for the master machine must be adopted.